| Abstract: | Austenitic stainless steel has been welded to coat pressure vessels in petrochemical plants. The material is highly susceptible to stress corrosion in chloride environments, which can damage the weld and lead to the rupture of the component. In this work we did the evaluation of the influence of welding parameters on the stress corrosion resistance of AISI 304 steel exposed to a magnesium chloride solution. AISI 304 sheets were manually welded using three different coated electrodes (AWS E309-16, E308L-16, E316L-16) and two heat inputs (5.0 and 9.0 kJ/cm). The welded samples were analysed by tensile strength tests, optical microscopy and corrosion tests carried out according to ASTM G36-73 guidelines. The results showed that the AWS E309-16 electrodes produced the best results due to the microstructure of the resulting weld metal. The presence of a network of ferrite particles in an austenitic matrix acts as a barrier to crack propagation, thus enhancing the resistance to stress corrosion of the material. This effect is associated to the morphology and distribution of the phase rather than its contents. Welding in a direction parallel to the stress axis using a relatively high heat input improved the stress corrosion of the material even further. The HAZ (Heat Affected Zone) of AISI 304 steel was highly susceptible to stress corrosion in chloride solution. The presence of carbide precipitates in the austenite grain boundary deteriorated the corrosion resistance of the steel, as they promoted anodic dissolution and the development of stress corrosion cracks. |
